So far I have used this a couple of times for wild camping. The bivi seems to be sturdily made, has plenty of room and I was pleased to find that I had no condensation at all within the bag, even under a tarp, so breathability seems pretty good. The built in mozzie net is a small removeable zipped mesh panel at face level and using it is a bit less claustrophobic than using the non mesh insert. The wire frame isn't really stiff enough to keep the mesh well away from your face but it is not so intrusive to prevent sleep.
The zip is probably about 1/3 length and gives enough room to get in an out without any difficulty but it has no baffle so I would be concerned about using this bivi bag in the open in a heavy downpour. One niggle is that the velcro flap/baffle that is meant to seal the zip junctions has been stitched in the wrong place (slightly too low) so at the junction of the zips I have a penny sized hole which obviously is big enough to let in water (or midges).
I will probably do a bit of modding to rectify this but I hope this is just a one off with my bag and not a design flaw. I think this is only good enough to use with a tarp but not in the open if there is heavy rain forecast.
For the price paid I'm reasonably happy with it but a bit more care in manufacture would have earned this 4 stars.